Excelsior JET

Your Java application is delivered in a portable bytecode form and runs on top of the Java Virtual Machine (JVM). The JVM is a part of the JRE that should be installed on every system on which your application runs.

The JVM executes the application and gradually improves its performance by optimizing the Java code at run time.

Fig 1. JVM warm-up cycle vs. steady performance of a native app

Put simply, when a user launches your application or a consumer turns on your Java-powered device, Java code performance is relatively low. The performance is improved to some extent only after the application has run for a while. Unfortunately, when it is re-started, the entire warm-up cycle gets repeated.

Suppose you had an automatic tool that optimizes Java code for your target platform before execution. Free of resource constraints inherent to run time optimizers, it processes all the code and optimizes it well.

You feed the application's classes to the tool, which optimizes them for performance and saves the results to disk. Now, you can deploy your Java application in optimized form so that it runs fast from the start on target systems.

What is that automatic tool we are talking about? Read on.

A Java application typically consists of class files and resource files, like images, which are packed into one or more jar files.

Using the Excelsior JET Optimizer, you convert the classes into highly optimized x86 code and create a native executable for Windows or Linux. This technique is called Ahead-Of-Time (AOT) compilation.

Fig 2. AOT compilation

Now, the original Java classes are no longer required for the application to run.

And you can launch the executable as you would a native application.

Upon startup, the application executable links to the Excelsior JET Runtime, which provides the Java platform API classes (also native compiled) and low-level runtime support routines necessary for Java applications, such as garbage collection.

Fig 3. The Runtime serves the compiled executable

Now, your Java application runs directly on the underlying hardware.

Finally, you can leverage Excelsior JET to create a professional installation for the optimized application.

With the help of the Excelsior JET Installation Toolkit, you can create a complete installation package that includes your optimized Java application, the Excelsior JET Runtime, and any additional files, like user's documentation, extra utilities, and so on.

Fig 4. Packaging the optimized application

The basic deployment procedure is very simple. The created installation package is a self-contained directory that can be installed on target systems by a simple copy operation. Another option is store it on removable media, such as a flash memory card or USB drive, enabling your end users to run the application without installation.

If necessary, you can wrap the package into Excelsior Installer bundled with Excelsior JET or use another setup generator of your choice.

The JRE need not be installed on target systems for your application to run.

Now you can ship your server-side and desktop Java applications or Java-powered devices to end users.

Fig 5. Java deployment simplified

Your Java application may need to load classes that are available only on a target system, downloaded from a remote host, or generated at run time. Examples are dynamic proxies, third-party plug-ins for your application, and JDBC drivers.

How does Excelsior JET cope with that? Easily.

The Excelsior JET Runtime includes a JIT compiler that transparently loads Java classes to the running application.

Fig 6. Dynamic class loading

One might ask: why do I need this big iron (JET Runtime) including all standard Java classes pre-compiled while my app uses only a few of them?

The JET Optimizer can compile your application's classes and required classes of the Java SE API together into a single executable. Then, you may leverage the Java Runtime Slim-Down deployment model to leave the unused parts of Java SE out of the application installer.

As a result, a complete application setup powered by Excelsior Installer can be substantially smaller than the Sun JRE alone.

This technique also helps you significantly reduce the disk footprint of your application compared to the Sun JRE footprint. It can save a fair bit of valuable space if your Java applications come pre-installed on removable media such as flash memory cards or USB drives.

We invite you to download a fully functional evaluation copy of Excelsior JET. While it is downloading, take a look at the Product Data Sheet that contains the full list of features and benefits offered by our product.

Find more information about how Excelsior JET can help you:

• improve application performance
• protect your intellectual property
• simplify deployment procedures